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General Category => TED5000 Support => Topic started by: GAR on August 04, 2011, 06:51:37 PM

Title: Hard wired communication link?
Post by: GAR on August 04, 2011, 06:51:37 PM
110804-1042 EDT

Why are there not TED models with hard wiring from the MTU to the RDU or Gateway to eliminate the unreliability of the power line communication path? It seems to me it would have been self-evident that when the 5000 series was created that a hard wire link would have been a better system design choice.

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Title: Re: Hard wired communication link?
Post by: rotus8 on August 04, 2011, 08:10:31 PM
The biggest reason is that code says you may not have low voltage wiring going from inside an AC panel to outside the panel, without the wiring being rated for the full AC requirement.
Title: Re: Hard wired communication link?
Post by: GAR on August 04, 2011, 08:56:58 PM
110804-1249 EDT

rotus8:

That is not an adequate reason to use power line communication. More than one way could be used to get the data from inside the panel to outside.

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Title: Re: Hard wired communication link?
Post by: rotus8 on August 05, 2011, 03:25:20 AM
You should go to work for TED and show them how to do it.
Title: Re: Hard wired communication link?
Post by: GAR on August 07, 2011, 06:41:04 AM
110806-2228 EDT

rotus8:

One way to do this is to make the MTU fit in a knockout so that on the outside of the main panel is a connector for the signal cable. There also are other ways to get the data out.

From the number of posts with with communication problems it seems that getting rid of the power line communication link would be a good idea. For my 1000 system I run an extension cord from the point where the MTU connects to the bus to where I have the display and data collection computer. So the display is connected into the extension cord. The computer elsewhere. I still have some dropout problems. Usually not too long.

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Title: Re: Hard wired communication link?
Post by: TEDSupport6 on August 11, 2011, 11:46:19 PM
Our research and development department is constantly working on ideas for improving TED for the future, particularly when it comes to MTU/Gateway communication. Once those ideas are proved effective, they are moved into production. Thank you for your feedback!
Title: Re: Hard wired communication link?
Post by: jrwalte on August 12, 2011, 08:06:12 PM
It isn't easy, but you can technically make a 'hardwire link' between the MTU and Gateway now.

You purchase an in-line filter and install it on a new breaker to isolate the breaker from the rest of your home. You then run a new electrical line from the isolated breaker to a new outlet that is in reach of your Ethernet network. The MTU/Gateway are now segregated on a filtered, dedicated electrical line.
Title: Re: Hard wired communication link?
Post by: cloudix on August 12, 2011, 08:37:54 PM
Why not use WIFI or Bluetooth as another option? forget the wires if you don't really need them.
Title: Re: Hard wired communication link?
Post by: GAR on August 12, 2011, 08:40:02 PM
110812-1218 EDT

jrwalte:

That is essentially what I do presently, except I do not have the in-line filter. I use an extension cord.

My point of this thread is that power line communication is a poor way to build a reliable communication system. The reliability is still poor when going thru the gyrations of testing and filtering. Whereas, with an isolated hard wired communication path the reliability would be extremely high.

I have customers sending large amounts of data (100s of millions of bytes) at 115 kbaud, with no error correction, and no errors over distances of hundreds of feet. I can subject the interconnect cable to a common mode voltage of 1000 V RMS at 60 Hz with no data errors. My path has optical isolation at both ends. I do not suggest that the TED system needs my kind of isolation, just that it use a hard wire connection. Probably with simple optical isolation at the MTU. High baud rate capability is not needed. A hundred bytes per second are probably adequate. So roughly 1200 baud would do.

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Title: Re: Hard wired communication link?
Post by: tazer on August 12, 2011, 09:18:09 PM
Why not use WIFI or Bluetooth as another option? forget the wires if you don't really need them.

Wireless does not work well from inside a metal enclosure, such as an electrical panel.

In my experience, PLC has worked pretty well. The only issue I had was when I upgraded to Insteon home control devices and the TED's data flow caused some interference. This was easily resolved by using an X10 filter (about 8 bucks, ebay) at the main panel and a dedicated circuit. This achieves a hardwired connection between MTU and gateway.

Let's say TED did offer a specific hardwired solution... You'd still have to run a wire from the electrical panel to your gateway. I don't see how that offers any real advantage over the filtered-dedicated-circuit approach. In either approach you're having to run a new wire from panel to gateway. The filtered-dedicated-circuit approach is superior in that the same wire provides both power and communication.  The only disadvantage is an additional thing (the filter) crammed into the space of your electrical panel.
Title: Re: Hard wired communication link?
Post by: GAR on August 13, 2011, 04:05:37 PM
1108123-0750 EDT

tazer:

The best signal to noise ratio and good bandwidth is going to be achieved with a separate hard wired or fiber communication path.

RF is vulnerable to microwave oven interference and other RF sources.

Power line carrier is a very noisy low bandwidth, and high attenuation path.

In most homes there is not too much problem to install some CAT-5 cable or other similar wire.

The TED system appears to be a one way path from the MTU to the RDU or Gateway. Thus, unless you can improve the signal to noise ratio (filters help this) the only way to reduce errors is to add redundancy to the data. This is won't solve the problem of total dropouts.

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Title: Re: Hard wired communication link?
Post by: rotus8 on August 13, 2011, 05:48:12 PM
The Gateway <-> MTU connection is bi-directional.
Title: Re: Hard wired communication link?
Post by: GAR on August 13, 2011, 06:17:53 PM
110813-1008 EDT

Even if the MTU communication path is bi-directional is it being used to request retransmission when errors are detected? Further is there any means employed to detect errors? The evidence from problems does not indicate any error correction. How many bytes of data are transmitted each second?

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Title: Re: Hard wired communication link?
Post by: jrwalte on August 13, 2011, 06:20:47 PM
Except most if not all state codes do not allow you to run low-voltage CAT5 into your service panel, and many of us do not have exposed service panels (they're flush in a wall) so we can't just attach a metal box to the external side of the service panel and install the MTU and the CAT5 into the new metal box.

TED has to think of all installations this product needs to work in, and so far no better option over PLC has been mentioned.
Title: Re: Hard wired communication link?
Post by: tazer on August 13, 2011, 09:13:44 PM
The TED system appears to be a one way path from the MTU to the RDU or Gateway. Thus, unless you can improve the signal to noise ratio (filters help this) the only way to reduce errors is to add redundancy to the data. This is won't solve the problem of total dropouts.

Have you tried using an in-panel filter and a dedicated circuit yet? Your other post mentioned using an extension cord but without a filter. The filter really is the key to having the dedicated circuit.
Title: Re: Hard wired communication link?
Post by: GAR on August 13, 2011, 10:09:29 PM
110813-13421 EDT

tazer:

With the extension cord method I am using and no in line filter I do not have a major problem. There are just random times and for moderately short periods there is loss of data. Some of the loss may actually be the MTU failing to send data. Had one time when the MTU quit for hours. I think I switched MTUs, but I might have just cut power to reboot the MTU.


jrwalte:

There is nothing that would prevent a fiber cable from going inside any cabinet. I will admit that ease of installation is probably the driving force behind the use of the power line. But then one has to go thru all these gyrations to solve miscellaneous problems. Most houses do not have many circuits that serve only one or just a few receptacles, and those circuits with only one outlet are usually dedicated to high power appliances. My extension cord across the basement floor is a simple present solution. The circuit to the bench where the RDU is located has several computers and other equipment running on the circuit. A separate circuit sometime is a possibility, but it is not a high priority. 

One distributor on the Internet said that they quit selling TED systems because customers were encountering too many problems. Thus, is ease of installation more important than a high reliability system and customer satisfaction?

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Title: Re: Hard wired communication link?
Post by: SherlockOhms on August 16, 2011, 06:26:17 PM
@Gar Everyone is pretty much correct in their reasoning.  The reason for PLC has to do with electrical code. Remember the system is used in a lot of different configurations. As some one said by code you can't mix low voltage and hi-voltage wiring. Specifically "all conductors must be rated for highest possible voltage used in the panel" so for US it would mean 300v typically. While it may seem so simple and make sense... its not that simple. As some one else mentioned wireless will have hard time going through metal box. Filtering a circuit and isolating communication link is really the best approach.
Title: Re: Hard wired communication link?
Post by: GAR on August 16, 2011, 10:53:07 PM
110816-1424 EDT

SherlockOhms:

I do not follow your logic.

Nothing prevents you from using 600 V wire.

Further in the Installation Guide Example 2 shows the MTU on the outside of the panel. Now you presumably already have 600 V wire to the inside, and outside 600 V is not required.

There are the other possibilities I mentioned previously, and others to get data from inside to outside.
1. Build the MTU so that a communication connector is on a hub that is put thru a knockout hole.
2. Use a fiber optic cable inside to outside.
3. Use ultrasonic or magnetic coupling from inside to out.
4. And I could think up other ways.

Power line communication may in reality be satisfactory, but its problems and limitations should be known by the customer beforehand.

.   
Title: Re: Hard wired communication link?
Post by: SherlockOhms on August 17, 2011, 01:07:05 AM
Let me know where we can purchase 600v Ethernet rated cable.

Your also assuming a single MTU installation.  In that case yes your ideas are fine and would work.

Now let's throw a curve ball.... how will you handle 4 MTU's across entire house?  Your willing to invest into fiber-optic line ran through the house? That may not always be an option.  Again it may be simple in your case personally... the goal however is to have a system that is easily installed in as many situations as possible.  Not many people are skilled enough to do the required fiber-optic wiring. At same time your making the system even more complicated and more expensive. 

Don't give up on PowerLine communication yet :) 
Title: Re: Hard wired communication link?
Post by: GAR on August 17, 2011, 03:04:09 AM
110816-1845 EDT

SherlockOhms:

If the MTU is outside the panel, then why do you need 600 V Ethernet cable?

If the connector is on the outside of the panel, but the MTU is on the inside, then again why do you need 600 V wire for the Ethernet cable? All you need is the surface of the panel as an isolation between the inside and outside wiring. Obviously I am assuming galvanic isolation between inside and outside in case of an internal short.

Further you could leave the MTU inside, use 600 or higher voltage wire to come outside the panel to the Ethernet isolation transformer, then regular CAT-5 cable.

Also I am not assuming an Ethernet source in the MTU, but that might be OK.

Basically in the 5000 system you go to Ethernet cable following the Gateway anyway.

.
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 20, 2011, 07:59:33 PM
Read through all of this I am still a little bit confused.
My idea was also to run a separate, filter isolated power cable through my attic to my office and provide the gate way with power and data from the MTUs.


Now here you guys mention a direct connection form the MTU to the Gateway.
Installing the MTU outside of the main panel should not provide a big problem. But how can I run a ethernet cable from the MTU to the gateway. There is no connector on the MTU for that, right ??? ???
Title: Re: Hard wired communication link?
Post by: GAR on August 20, 2011, 10:42:35 PM
110820-1313 EDT

PV-Skip:

When I started this thread I was asking why there were not hard wired versions of the TED system.

There are not any MTU to RDU or Gateway hard wired solutions except to use the power line.

The TED designers chose to to use power line communication. They have given some reasons for this. One reason not given is cost and the belief that power line communication provides for flexible and simple installation.

Simple is probably true if filters and experimentation to solve problems did not become a factor in installation or questions on why something was not working.

Cost is also probably true if unintended consequences are ignored.

Your only solution, without modification of the original components, is to install an in-line filter at the MTU location. On the output side of the filter connect the 120 V input to the MTU, and a new separate circuit to the location of the RDU or Gateway. This new circuit should have nothing on it except the RDU or Gateway. You have to operate in the 120 V mode because the in-line filter is only for one phase. But I would operate in the 120 mode anyway.

With the Ethernet connection from the Gateway to whatever (computer or network) you have electrical isolation, usually thru a coupling transformer, between the Gateway and the computer. Thus, the AC power to the computer can be and probably should be from some other circuit. This will reduce the noise from the computer power supply that gets into the power line communication cable.

The 1000 series RDU is a different problem. In this case, if the computer power cord has three prongs, then it should be powered from the power line communication cable so the computer EGC (equipment grounding conductor --- ground pin in the plug) is tied to the EGC of the the power line communication cable. This may require a plugin filter for the computer to minimize noise from the computer getting to the communication path. This ac supply source for the computer is to minimize ground path noise that might interfere with the USB communication path.

I have just received one each of these filters from Energy, Inc. These are in fact X!0 filters and probably can be obtained anywhere X10 is sold. The X10 part numbers are XPPF for the plug-in, and XPF for the in-line.

If you are using a single gateway, then all MTUs have to be on the load side of that single in-line filter.

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Title: Re: Hard wired communication link?
Post by: PV-Skip on August 22, 2011, 06:50:24 AM
Thanks Gar,
that was a excellent summary.
After digesting all the stuff yesterday I came to the same conclusion and ordered two in-line filters. I found a cheaper source though. . .
I just came from the attic installing a separate power-line for the gateway, running from the panel to my office and are waiting now  for the filter(s) before the final connection.

Two questions remains. Does it matter, if I connect both my MTUs and the Gateway on that filter, or should I have a filter for every MTU?
Secondly, I also have a Enphase microinverter system and an Envoy gateway for that, which sends its data over the house power lines.
So far they don't seem to have problems together.
My intention is, to have this Envoy also running on this special, filtered power line.
Do you think, that would create a problem?

Thanks for your help!
PV-Skip
Title: Re: Hard wired communication link?
Post by: GAR on August 22, 2011, 05:34:50 PM
110822-0814 EDT

PV-Skip:

Last week I ordered 1 in-line, and 1 plug-in filter from Energy, Inc. These arrived Saturday. These are actually X10 filters in X10 boxes with X10 instructions. In a separate thread I commented on my analysis and experiments to date.

Changing subject for a moment. The data sent from the 1000 MTU is in bursts of 100 milliseconds (0.1 second) every 1 second. The data burst is around 200 milliseconds for the 5000 and it appeared to be a lower signal level. I had sync problems getting the leading edge without other noise triggering. Also note that the 5000 sends data only once every 2 seconds. That is why the exported second data from the 5000 appears to provide duplicate data in 2 second blocks.

There is an intercept probability of two or more MTUs on the same circuit overlapping their transmission time. If this occurs there is loss of data or errors. The time clocks in the MTUs are relatively accurate, therefore the drift rate of one clock to another is rather slow. Suppose two MTUs on the same circuit start out with one transmitting just 0.1 second before the other. As the slow drift occurs let the first drift into the second and there will be errors for a long time depending upon the drift rate.

All the TED systems use 132 kHz for their carrier frequency. X10 apparently uses 120 kHz. Others may use slightly different frequencies.

I have no idea what two way communication TED uses, nor whether any collision detection and retransmission occurs on errors.

Back to your question. I would start with one in-line filter to a single dedicated circuit. On this circuit would be 1 MTU and 1 RDU or Gateway. Get several days of 1 second data. About 3.8 megabytes of exported data in a .CSV file per day. In the exported data there are 42 bytes plus line feed per second for the 1000. Each of these records has about 15 unnecessary bytes, and if the year had been excluded a few more.

Analyze this data for lost seconds.

Next add a second MTU and receiver to the circuit. Put these current sensors on the same wires that the first set of sensors are on. Collect data from both receivers and compare the lost seconds. This may provide an indication of the likelihood of intercept problems. However, it is all chance on what the relative drift rates are between the MTU clocks. The MTU in the 1000 series does not contain a real time clock. That is in the RDU. The timing of the 1 second rate of transmission will come from the MTU's microprocessor clock (its basic time source - probably a crystal oscillator). TED could add some randomized jitter to the 1 second to minimize collisions when two MTUs were on the same circuit. But all this is conjecture.

I do not run multiple MTUs, but running just one on a fairly clean circuit I get loss of data at times and for many seconds at times.

.   
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 23, 2011, 05:44:12 AM
Thanks again Gar,
got it so far. (Hopefully) ;D

I still don't know, how I can look for lost data or seconds.

PV-Skip
Title: Re: Hard wired communication link?
Post by: GAR on August 23, 2011, 06:37:33 AM
110822-2150 EDT

PV-Skip:

One second export from a 1000 system looks like the following:

"10/2/2010 11:11:59 PM","1.67","0","125.2"
"10/2/2010 11:12:01 PM","1.68","0","125.2"
"10/2/2010 11:16:29 PM","1.61","0","125.3"
"10/2/2010 11:16:30 PM","1.61","0","125.3"
"10/2/2010 11:16:31 PM","1.61","0","125.3"
"10/2/2010 11:16:32 PM","1.61","0","125.3"
"10/2/2010 11:16:33 PM","1.61","0","125.3"
"10/2/2010 11:16:34 PM","1.62","0","125.3"
"10/2/2010 11:16:35 PM","1.61","0","125.4"
"10/2/2010 11:16:36 PM","1.61","0","125.4"

After I remove some of the unnecessary stuff I get a result similar to this

23:16:32, 1.61, 0, 125.3

In the 5000 system they got rid of all those unnecessary quote marks. I think they still use AM and PM which makes no sense for data processing, or even thinking, and midnight should be 0.

You simply write a basic program to find a discontinuity in the sequencing of the 1 second increment data.

When a discontinuity in the seconds occurs, then output the full record before and after he occurrence. You don't need to remove the junk for this purpose. I do it to reduce the file size and make manual reading easier. What I also do for plotting is convert to decimal hours. So 23:16:23 becomes 23.8000 . Converting to decimal hours would not be useful for your purpose, but you will need to work in a mod 60 number range. Thus, 0 = 60 when comparing with 59. I think sufficient useful information would obtained from comparing seconds. Otherwise convert minutes to seconds and add to the seconds. Now you would work modulo 3600 .

.

 
Title: Re: Hard wired communication link?
Post by: GAR on August 23, 2011, 04:52:14 PM
110823-0821 EDT

PV-Skip:

Following is a sample of my data where there is lost data:

"7/22/2010 8:52:07 PM","3.51","0","123.7"
"7/22/2010 8:52:08 PM","3.51","0","123.7"
"7/22/2010 8:52:09 PM","3.51","0","123.7"
"7/22/2010 8:52:10 PM","3.51","0","123.7" ....... start of loss
"7/22/2010 8:52:53 PM","4.01","0","123.5" ....... end of loss
"7/22/2010 8:52:54 PM","3.78","0","123.7"
"7/22/2010 8:52:55 PM","3.5","0","123.6"

Notice the lost time between 52:10 and 52:53 . This is what you would be looking for in the data. Only one MTU is running.

This problem could be Microsoft (XP-Pro), MTU, RDU, or external noise interference.

One time I had the 1000 MTU quit sending data completely, the MTU runs without a command for data, and therefore every second should send data. I replaced that MTU with another one, but later, on the bench, the non-functioning MTU began working again. Note: just power on reset did not correct its problem. So I have no idea about the cause of this failure.

.

Title: Re: Hard wired communication link?
Post by: GAR on August 23, 2011, 06:04:45 PM
110823-0935 EDT

PV-Skip:

Another consideration on loss of data. What is the TED algorithm for calculating energy? If this is simply summing the 1 second power values divided by 3600 over some time period, then loss of data within that time period reduces the accumulated energy for that period.

If it is assumed that a good estimate of the power during the loss time is the average of the starting and ending powers of that period, then that average power value divided by 3600 and the result multiplied by the decimal time in hours of that loss period could be added to the other accumulated energy.

These problems would not need to be considered if the communication path was rock solid.

.
Title: Re: Hard wired communication link?
Post by: jrwalte on August 24, 2011, 12:55:44 AM
Two questions remains. Does it matter, if I connect both my MTUs and the Gateway on that filter, or should I have a filter for every MTU?
Secondly, I also have a Enphase microinverter system and an Envoy gateway for that, which sends its data over the house power lines.
So far they don't seem to have problems together.
My intention is, to have this Envoy also running on this special, filtered power line.
Do you think, that would create a problem?

Both MTUs, if communicating to 1 gateway, MUST be on the same side of the filter as the gateway. The purpose of the filter is to separate the electrical noise on either side of the filter and prevent pass-through to/from the breaker. If a MTU isn't on the same side of the filter as the gateway, it would get filtered out and wouldn't be able to communicate with the gateway.

A second benefit to me having to install an in-line filter where my home entertainment connects, it is stopped my LED lights from occasionally flickering. Apparently my electronics were causing some noise the LEDs were reacting to.
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 24, 2011, 06:36:10 PM
Thanks again Gar,
I exported the second data from the TED 5000.
had to format the cells  to se the seconds and it looks very good.
I did not go through all of them (would need an hour for that) but I compared the cell numbers with the second numbers in order to see, if there are seconds missing.
So far, so good.
But there could be some noise at times I did not look at. . .
And all that on the normal house network.
Since I have installed the dedicated power line over the weekend and are just waiting for the filters, I'll install everything on that line anyway.

For installing the filter(s) and going back just to the black wire on the MTU, I suppose both my MTUs have to be on the same side of the phase. A or B, right?
Title: Re: Hard wired communication link?
Post by: GAR on August 25, 2011, 05:06:55 AM
110824-2053 EDT

PV-Skip:

I think the question on the phases was answered, here or one of the other threads.

If you simply go to "export", select the averaging time as seconds, save to a file, open the file with Wordpad, then you have a human readable ASII data set. On 1000 series dumps you must use Wordpad because the file has no carriage return characters. On the 5000 series carriage returns are included and most text editors or word processor should provide a usable output.

.
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 25, 2011, 06:23:33 PM
Yeah, I can see the data nicely with excel.
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 26, 2011, 09:10:17 PM
Installed my dedicated, filtered line for the gateway last night.
Some hick-ups, but the corrupted data % is down to about 3 now.
Title: Re: Hard wired communication link?
Post by: GAR on August 26, 2011, 09:53:03 PM
110826-1351 EDT

PV-Skip:

What were the hick-ups?

.
Title: Re: Hard wired communication link?
Post by: PV-Skip on August 27, 2011, 12:20:44 AM
110826-1351 EDT

PV-Skip:

What were the hick-ups?

 After installing the filter and changing the setup to "120V (bk, wh)" it messed up my average values.
It doubled the "KWh used this Month" and "Projected KHh usage" and messed also up the use since midnight.
Had to erase the history last night and this morning I realized that the real time usage was a negative number now.

I assumed a failure of the 2 firmwares, which I installed again, but no luck.
Between all of this my usage jumped around and went up to over 5000 Watts with nothing running in the house.
Finally I read through the trouble shooting guide and found the suggestion to turn one of the main current sensors. Did not make sense to me at that time, but I did it anyway.
My ghost usage was cut in half, so I turned the other one too.
Now the red dots are facing the breakers and everything is running fine.

Ted from the Enphase forum explained the sensor problem to me and it made sense.
I could have also swapped the clamps or the sensing wires to the opposite side of the phase, but at that time I did not fully understand the implications of the accidental change of the power wire to the MTUs.
Title: Re: Hard wired communication link?
Post by: GAR on August 27, 2011, 06:47:56 AM
110826-2115 EDT

PV-Skip:

Your description of the problems tends to confirm my judgement that there are fundamental design defects in the 5000 series software. I do not know where or why, but various different problems that are discussed on this forum probably result from some fundamental defects in design. From the outside it is also very hard to know what is going on inside a complex "black box".

First, stored data should not be modified without your specific OK. So changing parameters or setup structure should not change data without your ability to save the data first first.

From experiments I have run on both the 1000 and 5000 where I use a single current sensor and observe the output power reading when I reverse the sensor orientation has shown no sign change. Ideally I would expect a sign change, but apparently there is no display of a sign. Thus, we do not really know what is happening internally. What does occur is if two sensors are used on one load wire the power reading is double the power reading of a single sensor when one is orientated opposite the other, and zero or near zero if phased the same. This is what is expected.

Investigating my defective 1000 series MTU I found the following:
Each current sensor has one red and one black lead.
Both sensors are made and phased identically. Thus, if orientated in the same direction on a single wire and both red leads are connected together, then voltages from black to red for each sensor will be nearly identical in both voltage and phase.
That this is correct I verified by measuring the voltage between the two black leads and it was essentially 0. This is expected when you measure the voltage difference between two identical voltages.
With about 12 amperes flowing thru the sensor the voltage from one sensor was about 175 millivolts RMS. With one sensor reversed the voltage difference between blacks was about 350 millivolts. As expected.
Internally on the PC board the red leads are both connected to the ground plane.
Thus, the circuitry on the board from the sensors is subtracting one sensor from the other electronically in order to add the two signals.

I have to stop the story at this point because there are problems with this website and I can not see what I am typing. The display keeps shifting from the cursor position.

.
Title: Re: Hard wired communication link?
Post by: GAR on August 27, 2011, 06:50:55 AM
110826-2249 EDT

I will continue tomorrow.

.
Title: Re: Hard wired communication link?
Post by: GAR on August 28, 2011, 12:43:41 AM
110827-1634 EDT

PV-Skip:

I have looked at the datasheet for the Cirrus CS5461A and there is a differential amplifier at the input to each analog channel (voltage and current). The two current sensor signals are essentially added by this differential input. Assuming a similar chip in the 5000 this would be the means to sum the two voltage sources (+ 120 and - 120 phases).

The digital output of average power is two's complement with a range of +/-1.0 . Thus, internally TED could derive sign information for power,

The voltage channel in the 1000 feeds the +Vin pin and I suspect the -Vin is connected to the ground plane. The input voltage divider consists of 120k ohms and 100 ohms. Thus, a 1000 to 1 divider, 120 V in is 120 millivolts to the Cirrus chip. The peak voltage for 130 V in is 1.414 * 0.130 or 0.183 millivolts. Saturation is 500 mVp-p.

For the 5000 series I suspect there is a similar voltage divider to the -Vin pin and thus twice the input voltage to the Cirrus chip.

Suppose the MTU is scaled so that for 240 V applied to the voltage input and 1 A resistive load only thru one current sensor, nothing thru the other sensor, then we expect the power reading to be 120 W. Without changing anything else except removing 120 V from the red wire, then the power reading should change to 60 W. With only the black and white voltage wires used it is necessary for the scaling constant to be doubled to get a correct reading.

Based on the description of your problem this implies that the scaling is being done in the wrong place. The history registers should always be in kW or kWh units. Any scaling of values to compensate for the hardware change between 120 and 240 should be done before that data is combined into the history registers.

Quote
I assumed a failure of the 2 firmwares, which I installed again, but no luck.
Between all of this my usage jumped around and went up to over 5000 Watts with nothing running in the house.
Finally I read through the trouble shooting guide and found the suggestion to turn one of the main current sensors. Did not make sense to me at that time, but I did it anyway.
My ghost usage was cut in half, so I turned the other one too.
Now the red dots are facing the breakers and everything is running fine.
This result makes no sense. So long as the power being displayed is derived from one MTU, then for the current sensors to work correctly both must have their dots toward the meter or alternatively toward the main breaker. Should not make any difference based on my experiments. If more than one MTU is used and the results are combined in a Gateway or RDU I have no idea whether some sign information is used in the combination.

Title: Re: Hard wired communication link?
Post by: GAR on August 30, 2011, 03:55:10 AM
110829-1929 EDT

PV-Skip:

I think you have indicated that you want to determine if you are being billed correctly.

My current thoughts are as follows:

Experiment with one TED system first. This means one MTU and one Gateway.

Use two in-line filters. These filters connect to two separate breakers, one on each phase, or one two pole breaker. These breakers will have no other load on either circuit beyond 1 MTU and 1 Gateway. This means there will be negligible voltage drop across these two breakers. just a few millivolts if that much. Therefore the 240 V input to the MTU is essentially directly from the main panel busbars. This voltage will be as close to the voltage measured in the power company meter as is feasible for you to obtain.

One in-line filter feeds the red wire of the MTU and the other in-line filter feeds the MTU black wire. Use the MTU black wire circuit to feed data to your Gateway. This arrangement reduces noise to the MTU black wire circuit from the main panel busbar, and simultaneously reduces the electrical loading of the transmitter in the MTU from devices that at not on the MTU black wire circuit. The only loading will be the Gateway.

The second in-line filter from the other phase allows that phase's 60 Hz voltage to get to the MTU red wire, and reduces noise from the main busbar getting to the MTU and possibly to the MTU black wire side. The filter also reduces loading on the MTU transmitter.

This arrangement will most closely approximate the same signals the power company meter sees.

You will operate in the 240 V mode.

Later I will describe a means to check the TED calibration independent of using the power company meter because that is what you want check.


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Title: Re: Hard wired communication link?
Post by: GAR on August 30, 2011, 06:29:50 AM
PC-Skip:

You need a high power load resistor to put across the 240 supply.

Most all resistors have a substantial temperature coefficient. This means when operating at a high load the resistance will be different than at room temperature with no current flow. Thus, you can not make an accurate resistance measurement at room temperature and use this for the resistance at high load. Even so you still have to measure voltage and this has to be squared to calculate power knowing the resistance. Thus, if a current meter and a voltmeter of about the same accuracy are used to measure power the voltmeter only with a precisely known resistance does not produce any better power accuracy.

One way to measure power at the high load condition is to measure voltage and current and multiply these together. Using somewhat reasonably priced digital multimeters, about $ 400 each, you can get about +/-1% accuracy. Thus, the power accuracy would be more in the range of +/-2%.

If you had very stable voltage, then one meter could be switched between measuring current and voltage. 

The Agilent U1272A might be a useful choice, and it has other uses. Ideally you would want two instruments so measurements could be made simultaneously. These are limited to 10 A. The chip in the TED1000 has very good linearity and thus extrapolation to higher power levels might not be too bad.

On the other hand if you had a standardized and calibrated TED 5000 it could be your simplest and most economically accurate method. In other words use somebody with better test equipment to calibrate the MTU at a price. Thus, turning the calibrated 5000 MTU into a standard. To do this you would need to determine how much variation occurred from opening and closing the current sensors.

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Title: Re: Hard wired communication link?
Post by: GAR on September 02, 2011, 08:52:55 PM
110902-1040 EDT

Back to my original discussion. Since that point I have learned a great deal more about the TED system.

Some definitions first:

PLC is a name (acronym) for power line communication. This uses a high frequency carrier to transmit data over conventional 120 V power wires in a home or building. TED uses 132 kHz, X10 uses 120 kHz, and others may be at different frequencies. Then there are various devices using the power system that may introduce noise into these frequency bands. Also there are loads that attenuate the signal level.

FILTER generally means to remove or separate. From dictionary.com for electronics the definition is:
"6. Electronics,  Physics . a circuit or device that passes certain frequencies and blocks others."

SIGNAL to NOISE ratio (S/N). How strong a desired signal (signal) is relative unwanted signals or random noise (noise). The higher this ratio the greater is the probability of correcting detecting and extracting data from the desired signal. This ratio can be improved by increasing the transmitting power, filtering to reduce excess noise, reducing noise at the source, and better detection means, such as correlation detection.


Starting with X10 type systems. This system concept is based on the ability to have many different transmitting locations within the power distribution system of a building, and to have many different distributed receiving locations. This has to be viewed as a big network of parallel wires onto which a signal is injected somewhere (transmitted), and that can be received anywhere else. This has major problems from two sources --- shunting loads that attenuate the transmitted signal, and noise generators.

I believe the TED 1000 system started out with the X10 concept that would allow the MTU to be located at the main panel, and then the RDU could be plugged into any outlet for viewing data. This flexibility and no wire installation were selling points. From a marketing point of view seems to make sense. But from a technical view it is unreliable.

Problems were discovered. Namely errors or the system did not work. Thus, in each individual case patchwork solutions are suggested. Experimentation is required and somewhat indirect means are used to see if an improvement occurs. In many cases I suspect that operation may be marginal. Why should a receipt of 20 % bad packets be considered acceptable?

One of the solutions is filters. This is good as a starter. But more tha that should be done.

What is being called a filter I would rather call a filter-isolator to be more descriptive. The word filter being used to mean high attenuation of unwanted signals from the input side of the filter to the output side. This would reduce noise or other signals on the output side of the filter for the TED components of interest on the output side from the noise and other signals that originate on the input side of the filter. This I could do nicely with a cascaded sequence of L-C low pass filter stages. Series inductance and shunt capacitance. But this would be bad for the TED system on the output side because of the last capacitor in the filter. This capacitor looks like a short to the TED transmitter at its carrier frequency. A short to the transmitter lowers its output signal, thus reducing the S/N at the receiver.

So a filter alone is not the solution. At the filter output there needs to be a high output impedance at the TED carrier frequency. Now the TED transmitter won't be heavily load and its signal level will be large. To distinguish the required filter device from an ordinary Corcom filter, such as a 5VR1, I would prefer to call the TED filter a "filter-isolator". I might point out that I have probably 20 or more filters like the 5VR1 scatter through my house. These are on all my fluorescent fixtures to reduce radio noise from the lights.

Note: the filters supplied by TED are X10 filters and these are a "filter-isolator, and do a reasonably good job such that if the TED setup is as I describe next it should perform in a rock solid fashion relative to S/N.

The way to solve the power line communication problem is:

1. Erase the concept that any circuit in the house can be used for for this PLC. Means there is going to be a dedicated circuit for each Gateway or RDU and nothing else is on the circuit.

2. An in-line filter-isolator is installed at the main panel. There is no choice, you use the in-line filter-isolator. If the Gateway uses the red input wire, then a second in-line filter-isolator is required. Again, no choice it must be used.

3. This will be classified as an isolated circuit. There must be nothing else connected to this circuit, except 1 Gateway, and up to 4 MTUs that are associated with this Gateway.

4. Following this approach there should be rock solid communication with no communication problems if all the components are good. I expect bad packets to be essentially 0.

An experiment I ran earlier today with a plug-in filter-isolator as the filter and only a 5000 Gateway and 1 MTU produced a good signal. Adding a resistive load, a 1500 W heater at low power, 735 W (6.13 A at 120 V 19.6 ohms), reduced the signal level to 2/3. Without the in-line filter-isolator, in a normal house with large electrical loads, there could be far more attenuation of the transmitted signal than with the low power heater. That the in-line filter-isolator provides a series high impedance at 132 kHz is why its use prevents loading down of the transmitter from shunt loads on the input side of the filter

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Title: Re: Hard wired communication link?
Post by: tazer on September 03, 2011, 10:40:06 PM
1. Erase the concept that any circuit in the house can be used for for this PLC. Means there is going to be a dedicated circuit for each Gateway or RDU and nothing else is on the circuit.

2. An in-line filter-isolator is installed at the main panel. There is no choice, you use the in-line filter-isolator. If the Gateway uses the red input wire, then a second in-line filter-isolator is required. Again, no choice it must be used.

3. This will be classified as an isolated circuit. There must be nothing else connected to this circuit, except 1 Gateway, and up to 4 MTUs that are associated with this Gateway.

4. Following this approach there should be rock solid communication with no communication problems if all the components are good. I expect bad packets to be essentially 0.

Yep, that's really the way to go, and it's what I've been doing here for a couple of months now. It also keeps TED and the Insteon devices separate, since they don't play nicely. I would contend that it achieves what you set out for in the original post for this thread. What should be offered is a single integrated device that is both MTU and filter, and offers a dedicated lead for wiring to the branch circuit where the gateway would be installed. This would differentiate a professional TED install from an amateur one. It might require some of the less tech-savvy users to hire an electrician to wire the dedicated circuit, but that's true of many home improvement tasks. Oh, and put WIFI in the Gateway too, so the Gateway can be located close to (but not inside) the panel without the worry of having to run cat 5 to an arbitrary location.

Although I must say, the TED worked remarkably well before I did the dedicated circuit. The same techniques that were used to eliminate noisy devices from the X10 network sufficed to keep the house clean for TED traffic. The only complaint was that it gave some of my older X10 devices some grief, and the Insteon devices were the final straw the broke the camel's back (the Insteons were more reliable but the dimmers exhibited a weird intermittent flicker that was only present when the MTU was installed).
Title: Re: Hard wired communication link?
Post by: jrwalte on September 03, 2011, 11:22:09 PM
The gateway/MTU doesn't have to be alone. With a wall plug-in filter, it can work fine behind an in-line filter with other electronics on the same filtered breaker. I have a 15A plug-in filter for a UPS, 2 PCs, subwoofer, receiver, xbox 360, router, switch, and cable modem, that are on the same in-line filtered breaker as the gateway and I have no issues. Without the plug-in filter, the gateway has issues and without the in-line filter the gateway wouldn't work.

So it isn't necessary to install a dedicated circuit for the gateway if you can filter other devices on the same circuit with plug-in filters.
Title: Re: Hard wired communication link?
Post by: GAR on September 04, 2011, 12:12:21 AM
110903-1518 EDT

tazer:

Yes it does accomplish much of the goal I set forth in my original post.


jrwalte:

Sure the plug-in filter is a fairly reasonable solution to adding other loads on the same circuit, but it does not eliminate voltage drop changes thru the breaker to the isolated circuit from the variable loads on the isolated circuit. This drop may be small most of the time, but there are a lot of breaker panels and breakers that are not as good as Sq-D QO units. However, there was a time when Sq-D made some panels with aluminum busbars and these could be classified as very poor. I am not sure if this was done in the QO series.

With just TED components on the circuit there is virtually no voltage drop from the breaker interface to the bus and the breaker even with relatively high interface resistance. So TED sees bus voltage.

If you want accurate power measurements, then incorrect voltage to the MTU should be eliminated. I do not have a good solution for the voltage drop from the meter and thru the main breaker to the busbars.

What I was suggesting as a standard approach should produce the least problems for the average user without all sorts of experimenting to solve problems.

There seem to be enough problems from the start that any procedures that can be employed that almost certainly eliminate questions should be employed.

Additionally a lot of electricians need work.